1. Field of the Invention
This invention relates to a novel liquid crystalline compound useful for display elements and a liquid crystal composition containing the same.
2. Description of the Related Art
Liquid crystal substances and their compositions have been used for various display devices utilizing the dielectric anisotropy (hereinafter abbreviated to .DELTA..epsilon.) and optical anisotropy (hereinafter abbreviated to .DELTA.n) in the liquid crystal phases thereof.
Liquid crystal display modes include various ones corresponding to the electrooptical effects to which the modes are applied, such as those of electric field control birefringence type (ECB type), twisted nematic type (TN type), super twist birefringence type (SBE type), dynamic scattering type (DS type), Guest-host type, etc. Liquid crystal materials used for display devices should be together provided with various specific features such as a broad mesomorphic range, a low viscosity, a large positive .DELTA..epsilon. value or negative .DELTA..epsilon. value and no large change in various specific features of display elements (particularly threshold voltage) over a broad temperature range, etc., depending on the respective display modes and also depending on various specific features required for display elements.
At present, however, there is no single compound which is practically usable in the aspects of mesomorphic range, operating voltage and response properties. Thus, mixtures of several kinds of liquid crystal compounds or mixtures of several kinds of liquid crystal compounds with compounds latently having liquid crystalline properties or non-liquid crystal substances have been practically used.